(a) Field of the Invention
The present invention relates to a method for fabricating a semiconductor device, and more particularly to a method for forming a contact hole for a dual damascene interconnection in the semiconductor device.
(b) Description of the Related Art
Recently, known dual damascene processes have been used for formation of metal interconnections in semiconductor integrated circuit devices. The known dual damascene process includes forming contact holes defining interconnection regions, and completing dual damascene interconnections by filling the interconnections with a conductive film using a physical deposition process.
FIGS. 1 to 4 are sectional views illustrating a method for forming a contact hole for a dual damascene interconnection in the conventional semiconductor device.
As shown in FIG. 1, an etch stop film 104 and an insulating 106 are sequentially formed on a lower metal film 102 made of copper (Cu). A first photoresist film pattern 108 is formed on the insulating film 106. Then, a via hole 110 is formed to expose a portion of a surface of the etch stop film 104 through the insulating film 106. The via hole 110 is formed by performing an etching process using the first photoresist film pattern 108 as an etching mask.
As shown in FIG. 2, the first photoresist film pattern 108 is removed, and the via hole 110 is filled with a photoresist film used as a sacrificial film 112. After forming the sacrificial film 112, the sacrificial film on the insulating film 106 is removed by performing a known etch back process. Subsequently, a bottom antireflective coating (BARC) film 114 is formed on the insulating film 106 and the sacrificial film 112.
As shown in FIG. 3, a second photoresist film pattern 116 is formed on the BARC film 114. An exposed portion of the BARC film 114 is removed by performing an etching process using the second photoresist film pattern 116 as an etching mask. Thereafter, exposed portions of the insulating film 106 and the sacrificial film 112 are removed to form a trench 118.
As shown in FIG. 4, the second photoresist film pattern 116, the BARC film 114, and the sacrificial film 112 are sequentially removed to expose a portion of the etch stop film 104. Then, the exposed portion of the etch stop film 104 is removed to form a contact hole, which includes the via hole 110 for exposing a portion of a surface of the lower metal film 102 and the trench 118.
By the above described method, the sacrificial film 112 is formed in order to prevent the lower metal film 102 from being etched when the etch stop film 104 is removed to form the trench 118. However, an additional ashing process is required to remove the sacrificial film 112. Additionally, the exposed surface of the lower metal film 102 is corroded or oxidized as the lower metal film 102 is exposed after removal of the etch stop film 104.